Adam Vinatieri kicked a 51-yard field goal on the final play tonight to give the Indianpolis Colts a 23-20 victory over the Chargers before 68,428 at Qualcomm Stadium.

The kick came two plays after Colts quarterback Peyton Manning completed a 14-yard pass to Marvin Harrison on a fourth-and-inch play from the Chargers 48 to put Vinatieri just inside his maximum range.

Vinatieri's kick dropped the Chargers to 4-7 and kept them two games behind Denver in the AFC West race with with five games to play. Earlier in the day, Oakland upset the Broncos 31-10 in Denver -- meaning a fourth straight Charger win over the Colts would have left them a game behind Denver with five to play.

Manning, who completed 32 of 44 passes for 256 yards, launched the game-winning drive from the Colts 30 with 1:26 to play.

The Chargers tied the game after making a third-and-one stand at the Colts 39 when linebackers Shaun Phillips and Jyles Tucker dropped Addai for a two-yard loss. Up to that point, the Colts had converted 10-of-15 third-down conversions.

After a 54-punt by the Colts Hunter Smith, the Chargers took over at their 13 with 3:16 to play.

Four straight completions by Rivers gave the Chargers a first down at the Indianapolis 37 at the two-minute warning.

Coming out of a 10-10 tie at intermission, the Chargers were apparently driving for a go-ahead score with a first down at the Colts 12 after just three plays.

Two runs by Tomlinson positioned the Chargers for a third-and-seven at the Colts nine only to have right tackle Jeromey Clary draw a five-yard penalty for a false start.

On third-and-12 from the 14, Rivers was stripped of the ball by Colts defensive end Robert Mathis at the 24. Mathis also scooped up the lose ball and ran it out to the 34 before being tripped up by Charger guard Mike Goff.

Manning drove the Colts to a go-ahead touchdown, converting three straight third-down plays during a 13-play drive that consumed seven minutes and 10 seconds.

The Chargers almost mounted a goalline stand like the one that turned around the momentum against the Jets earlier this season.

A seven-yard run by Dominic Rhodes gave the Colts a first-and-goal at the one. Three plays later, the Colts were still at the one.

But on fourth down, Rhodes escaped the coverage of middle linebacker Stephen Cooper to catch a one-yard scoring pass from Manning.

The Colts stretched their lead to 10 points on their next possession on a 38-yard field goal by Adam Vintieri after a pair of disputed calls went against the Chargers.

A pass interference call against free safety Eric Weddle gave the Colts a first down at midfield on a third-and-seven play. And an apparent fumble recovery by the Chargers was ruled an incomplete pass after Antoine Cason stripped Gonzalez of the ball on a completion over the middle. Cromartie had scooped up the lose ball.

The Chargers scored on their possession after the field goal on a one-yard touchdown reception by Jacob Hester -- the catch being the rookie fullback's third in a 70-yard drive. Hester was in the game after the Chargers lost fullback Mike Tolbert with a shoulder injury in the third quarter.

The first-half momentum swung temporarily on a rare interception for both Manning and the Chargers.

With the score tied 3-3, Manning threw deep over the middle for Marvin Harrison from the Colts 44. But Quentin Jammer swept in from the right side and intercepted the ball before it reached Harrison, who was a step behind the coverage.

The interception was the first by Manning in 140 attempts and first by the Chargers in 185 attempts.

Rivers then drove the Chargers 89 yards to a 10-3 lead, capping the drive with a 39-yard scoring strike to Vincent Jackson over the middle. Jackson made a leaping catch at the Colts five between middle linebacker Gary Brackett and safety Melvin Bullitt and backed into the endzone.

The key play on the drive was a third-and-seven Rivers completion to Malcolm Floyd for 23 yards from the Chargers 14.

Alas, the lead was short-lived. Manning immediately drove the Colts 71 yards to a tying touchdown, which came on a disputed play with 38 seconds to go in the half.

On third-and-two from the Charger 13, Anthony Gonzalez scored on a pass in the left flat that the Chargers claimed involved an illegal pick.

As Reggie Wayne came off the line of scrimmage as the outside receiver, he made contact with both Jammer and Warren Cromartie as Gonzalez broke to the outside from the slot.

The key play on the drive was a 23-yard run by Joseph Addai on a third-and-one from the Colts 38. Addai powered over the left side, then cut back and broke into the clear.

The game opened with an exchange of punts followed by an exchange of field goals.

The Colts mustered a pair of first downs on their first two possessions while the Chargers twice went three-and-out.

Manning drove the Colts 52 yards to Charger five on the third Indianapolis possession, the drive culminating in a 23-yard field goal by Vinatieri.

The Chargers immediately answered with a 35-yard Nate Kaeding kick after being stopped at the Colts 17. The key play in the drive was a 31-yard Rivers completion to Floyd up the left sideline on a third-and-two call. The completion on the final play of the first quarter was the Chargers initial first down of the game.

The Chargers were without defensive tackle Luis Castillo, who was made inactive before the start of the game with a groin injury. The Colts were without All-Pro safety Bob Sanders.